1. Field of the Invention
The present invention relates to a matrix-type liquid crystal display panel and, more particularly, to the method of driving such a liquid crystal display panel provided with a plurality of switching transistors connected to respective picture elements available for matrix display patterns.
2. Description of Prior Art
Conventionally, it is well known that, by providing a number of switching transistors in a matrix formation inside a liquid crystal display panel of a matrix-type liquid crystal display unit, a sharp-contrast display substantially equivalent to any static driver system can be realized, even when executing multi-line multiplex driving using a low duty ratio. Normally, such a matrix-type liquid crystal display panel has the circuit configuration shown in FIG. 1 (A) with signal waveforms as in FIG. 1 (B). In FIG. 1, reference number 11 indicates the liquid crystal display panel, in which switching transistor 11-c is connected to the crossing point of the row electrode 11-a and the column electrode 11-b. Reference number 11-d indicates a capacitor substantially made of liquid crystal layers. Reference number 12 indicates the row electrode driver comprised of shift-registers where the clock pulse .phi.1 sequentially shifts the scan pulse S before the phase-shifted scan pulse S is eventually delivered to respective row electrodes. If the total scan time is designated as T and the number of scan lines as N, then the width H of the scan pulse can be denoted by H=T/N. A pulse voltage of width H is sequentially delivered to each row electrode so that a number of thin-film transistors in each row is activated from row to row. Reference number 14 indicates the column electrode driver comprised of shift-registers and sample-hold circuits, which samples the data signal transmitted in series from the data controller synchronous with clock pulse .phi.2, at the timing dealing with each column, and then outputs the sampled value to respective electrodes after holding it for the 1-H scan period. To drive liquid cyrstals using AC current, a data signal waveform is supplied while inverting its polarity in each scan line. When driving is performed using the method described above, the total scan period T is computed by the formula T=(width H of the scan pulse) X (number N of scan lines), but, since it is necessary to invert the polarity of the data signal waveform in every scan line to drive liquid crystals using AC current, the frame frequency "f" of the votage supplied to liquid crystals is lowered to 1/(2T), thus unavoidably causing flicker in the display.